Positive and negative feedback by AGN jets in high‐redshift galaxies

Gaibler, Volker

doi:10.1002/asna.201412061

Cited by 6 publications

(5 citation statements)

References 35 publications

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“…Since we did not change the cloud properties systematically in our study, we cannot assess the impact of variations in the typical sizes clouds or cloud complexes, e.g. with redshift (Gaibler 2014). We only vary the the winds striking the clouds, but we too find that simultaneous positive and negative feedback is possible in the same galaxy provided that the winds will depend on time and location within the galaxy.…”

Section: Discussionmentioning

confidence: 96%

AGN Outflow Shocks on Bonnor–Ebert Spheres

Dugan

Gaibler

Bieri

et al. 2017

ApJ

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Feedback from Active Galactic Nuclei (AGN) and subsequent jet cocoons and outflow bubbles can have a significant impact on star formation in the host galaxy. To investigate feedback physics on small scales, we perform hydrodynamic simulations of realistically fast AGN winds striking Bonnor-Ebert (BE) spheres and examine gravitational collapse and ablation. We test AGN wind velocities ranging from 300-3,000 km s −1 and wind densities ranging from 0.5-10 m p cm −3 . We include heating and cooling of low-and high-temperature gas, self-gravity, and spatially correlated perturbations in the shock, with a maximum resolution of 0.01 pc. We find that the ram pressure is the most important factor that determines the fate of the cloud. High ram pressure winds increase fragmentation and decrease the star formation rate, but also cause star formation to occur on a much shorter time scale and with increased velocities of the newly formed stars. We find a threshold ram pressure of ∼ 2×10 −8 dyne cm −2 above which stars are not formed because the resulting clumps have internal velocities large enough to prevent collapse. Our results indicate that simultaneous positive and negative feedback will be possible in a single galaxy as AGN wind parameters will vary with location within a galaxy.

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Section: Discussionmentioning

confidence: 96%

AGN Outflow Shocks on Bonnor–Ebert Spheres

Dugan

Gaibler

Bieri

et al. 2017

ApJ

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“…The drag of molecular gas by the radio jet is not expected to be very significant on large spatial scales, principally because it requires moving very dense small clumps. Models indicate that the acceleration timescale of the dense clumps are generally longer than the dynamical timescale of the system (Wagner et al 2012;Li & Bryan 2012Gaibler 2014). A preferred scenario is cold gas (re-)formation from a hotter but low entropy gas within the inner radii of the ICM that is lifted by the AGN jets and bubbles (Revaz et al 2008).…”

Section: Origin Of the Cooling Gasmentioning

confidence: 99%

Ubiquitous cold and massive filaments in cool core clusters

Olivares

Salomé

Combes

et al. 2019

A&A

137

165

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Multi-phase filamentary structures around Brightest Cluster Galaxies (BCG) are likely a key step of AGN-feedback. We observed molecular gas in 3 cool cluster cores: Centaurus, Abell S1101, and RXJ1539.5 and gathered ALMA (Atacama Large Millimeter/submillimeter Array) and MUSE (Multi Unit Spectroscopic Explorer) data for 12 other clusters. Those observations show clumpy, massive and long, 3-25 kpc, molecular filaments, preferentially located around the radio bubbles inflated by the AGN (Active Galactic Nucleus). Two objects show nuclear molecular disks. The optical nebula is certainly tracing the warm envelopes of cold molecular filaments. Surprisingly, the radial profile of the Hα/CO flux ratio is roughly constant for most of the objects, suggesting that (i) between 1.2 to 7 times more cold gas could be present and (ii) local processes must be responsible for the excitation. Projected velocities are between 100-400 km s −1 , with disturbed kinematics and sometimes coherent gradients. This is likely due to the mixing in projection of several thin (as yet) unresolved filaments. The velocity fields may be stirred by turbulence induced by bubbles, jets or merger-induced sloshing. Velocity and dispersions are low, below the escape velocity. Cold clouds should eventually fall back and fuel the AGN. We compare the filament's radial extent, r fil , with the region where the X-ray gas can become thermally unstable. The filaments are always inside the low-entropy and short cooling time region, where t cool /t ff <20 (9 of 13 sources). The range t cool /t ff , 8-23 at r fil , is likely due to (i) a more complex gravitational potential affecting the free-fall time t ff (sloshing, mergers. . . ); (ii) the presence of inhomogeneities or uplifted gas in the ICM, affecting the cooling time t cool . For some of the sources, r fil lies where the ratio of the cooling time to the eddy-turnover time, t cool /t eddy , is approximately unity.

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“…Galaxies in which the conditions for positive feedback by AGN jets may be optimal are high-redshift gas-rich disc galaxies (Gaibler 2014). If an AGN jet propagates perpendicular to the gas-rich galactic disc, its interaction depth is short (of order the disc height) resulting in comparatively weak negative feedback (Sutherland & Bicknell 2007).…”

Section: Positive Feedbackmentioning

confidence: 99%

Galaxy‐scale AGN feedback – theory

et al. 2016

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Powerful relativistic jets in radio galaxies are capable of driving strong outflows but also inducing star-formation by pressure-triggering collapse of dense clouds. We review theoretical work on negative and positive active galactic nuclei feedback, discussing insights gained from recent hydrodynamical simulations of jet-driven feedback on galaxy scales that are applicable to compact radio sources. The simulations show that the efficiency of feedback and the relative importance of negative and positive feedback depends strongly on interstellar medium properties, especially the column depth and spatial distribution of clouds. Negative feedback is most effective if clouds are distributed spherically and individual clouds have small column depths, while positive feedback is most effective if clouds are predominantly in a disc-like configuration.

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Positive and negative feedback by AGN jets in high‐redshift galaxies

Cited by 6 publications

References 35 publications

AGN Outflow Shocks on Bonnor–Ebert Spheres

AGN Outflow Shocks on Bonnor–Ebert Spheres

Ubiquitous cold and massive filaments in cool core clusters

Galaxy‐scale AGN feedback – theory

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